[whpalmer4]

No, it isn't possible to do every function in OmniFocus via the keyboard, just most of them. The one that comes to mind is jumping from the main window to the Inspector and back. You can summon or dismiss the Inspector from the keyboard, but you can't get over there and back. I would like that very much, as I usually have the Inspector over at the right edge of the screen, and most of the stuff I click on is at the other side of the screen, making for a long trip even with mouse acceleration.

I find OmniFocus to be sluggish enough with my data that the disruption caused by having to move my hand a few inches to tap the trackpad isn't a problem. The time needed to actually complete tasks is much greater than the time taken to process them even if I have to remove my hands from the keyboard, drop to the floor and do 10 pushups. If the task takes an hour, does it really matter whether checking it complete takes 1 second, or 3? :-)